class People:
     def __init__(self, name, age):
         self.name = name
         self.__age = age
     def __sayHello(self):
         print('Hello, 大家好')
     def greeting(self):
         self.__sayHello()
     def getAge(self):
      return self.__age
xiaolan = People('小蓝', 10)
xiaolan.greeting()
print('我叫{}，今年{}岁了。'.format(xiaolan.name, xiaolan.getAge()))


class Animal:
    type = '动物'
    food = '食物'
    def eat(self):
        print('{}吃{}'.format(self.type, self.food))
class Cat(Animal):
    pass
cat = Cat()
cat.eat()
cat.type = '猫'
cat.food = '鱼'
cat.eat()